1. Technical Field of the Invention
The present invention relates to a levitation air plate, and more particularly to a levitation air plate used for noncontact conveying devices that produce flat panel displays (FPDs) such as large-scale liquid crystal displays (LCDs) and plasma displays (PDPs), solar cell panels (solar panels) and so on.
2. Description of the Related Art
When producing FPDs, solar panels and the like, a method of enlarging one panel to increase production efficiency is employed. Then, contact-type conveyors using conventional abacus-type rollers for conveying FPDs have disadvantages in conveying an enlarged glass with thin-wall while increasing velocity; minimizing stress; and conveying with floating amount maintained in high accuracy etc., so that noncontact and air-float conveying is desired.
This noncontact and air-float conveying generally ejects airs from plate-shaped boards to float a substance being conveyed such as a glass. In order to eject airs, there are a method of ejecting airs through fine pores of a porous material such as carbon and a method of drilling small holes through a thick plate with high rigidity to eject airs through these holes.
In processes of checking and coating circuit patterns drawn on a glass to be conveyed, it is necessary to maintain floating amount of the glass in high accuracy. Therefore, it is required a method of floating the glass while maintaining its high rigidity to straighten warpage of the glass.
Conventionally, in order to float and hold a glass or the like while maintaining its high rigidity, combining hydrostatic air bearings of porous body with throttles and suction holes is proposed. But, it is difficult to manufacture a large-scale structure of porous body with throttles in high accuracy, so that a large-scale, for example, 2 m×2 m-level product was not realized. In addition, to manufacture air bearings of the type that many small holes are drilled in a thick plate with high rigidity, there is a problem that enormous time and expenses are needed.
Then, the present invention has been made in consideration of the above problems in the conventional levitation air plates, and the object thereof is to provide a levitation air plate that can be easily manufactured and can float a substance being conveyed such as a glass while maintaining its rigidity and controlling a floating amount in high accuracy.